Gear and method of making the same

ABSTRACT

In order that a worm  1  is rotated, a clearance (a region constituting a clearance portion between bearings and a worm gear) is formed (FIGS.  4 ( 1 ) to ( 3 )) in an upper surface of a base plate  3 . A mold  12  for forming a lower half region of the worm therein is formed (FIG.  4 ( 8 )). A material  5  for the worm is deposited (FIG.  4 ( 9 )) to a height equal to that of a lower half region plus that of an upper half of the worm. An upper half of the worm is formed (FIGS.  4 ( 10 ) to ( 12 ). Finally, the material  13  in the clearance between the base plate  3  and gear  1  is removed (FIG.  4 ( 13 )).

TECHNICAL FIELD

This invention relates to gears of the sizes in the order of submicronto centimeter applied to a micro-machine, and more particularly to gearsobtained by forming one of projection type teeth, magnetic teeth andelectrostatic teeth on circumferential surfaces of worms the axes ofrotation of which are horizontal, perpendicular or inclined with respectto their base plate surfaces, or spur gears the axes of rotation ofwhich are horizontal or inclined with respect to their base platesurfaces, or bevel gears the axes of rotation of which areperpendicular, horizontal or inclined with respect to their base platesurfaces; and a method of manufacturing the same gears.

BACKGROUND ART

A combination of a worm and a worm gear used in a regular machine isshown as an example of a gear in FIG. 18. A spur gear placed with theaxis of rotation thereof set perpendicular to its base plate surface asshown in FIG. 17, and provided with projections on a circumferentialsurface thereof has a shape easily formed by the film formationtechniques and fine processing techniques used in a related artsemiconductor process. However, a gear other than such spur a gear andhaving a complicated shape, for example, a gear having helical teeth,such as a worm is not being manufactured.

A gear having magnetic teeth instead of projection type teeth on acircumferential surface thereof is proposed in Japanese Patent Laid-OpenNo. 56146/1997. The magnetic teeth of this kind of gear are formed on aflexible base plate by using a semiconductor process separately from agear base. The flexible base plate on which the magnetic teeth areformed is thereafter wound around a gear base to complete a magneticgear. However, according to this method, gears of sizes in the order ofup to around millimeter can be manufactured but it is difficult tomanufacture gears of sizes in the order of micron and submicron.

A driving actuator (motor) to be incorporated in a micromachine demandsto be microminiaturized. A microminiaturized actuator generates a lowpower. In order to operate a micromachine with a low generated power, itis necessary that power transmission gearing having a high reductionratio be provided in its power transmission path. The above-mentionedgears, i.e. a gear having projections on a circumferential surfacethereof, a gear with magnetic teeth formed on a circumferential surfacethereof and a gear with electrostatic teeth formed on a circumferentialsurface thereof are effectively used for this gearing.

The present invention provides gears mentioned above and formed onvarious base plates, such as a silicon base plate, a glass base plate, aceramic base plate, a plastic base plate, a metal base plate and thelike.

The gears to which the present invention is applied are a gear capableof being formed on a front surface and a rear surface and in an innerportion of a base plate, having projections on a circumferential surfacethereof and rotated with other gear meshed therewith, or a magnetic gearrotated by a magnetic force, or an electrostatic gear rotated by anelectrostatic force. In the case of the spur gear shown in FIG. 15, thegear is formed of a complicatedly shaped gear, for example, a helicallyshaped worm shown in FIGS. 1 and 2, a spur gear shown in FIG. 7 the axisof rotation of which is parallel to a base plate surface, a spur gearthe axis of rotation of which is inclined, a bevel gear shown in FIG. 9and an inclined bevel gear, etc., which are other than a spur gear theaxis of rotation of which is parallel to a base plate surface, and thesecomplicatedly shaped gears are indispensable to the practicalutilization of a micromachine.

The present invention has been made in view of these points, andprovides worms the axes of rotation of which are perpendicular, inclinedand horizontal with respect to base plates thereof, spur gears the axesof rotation of which are horizontal and inclined with respect to baseplates thereof, and bevel gears the axes of rotation of which areinclined, perpendicular and horizontal with respect to base platesthereof on all of which teeth of one of a gear having projections on acircumferential surface thereof, a gear having magnetic teeth on acircumferential surface thereof and a gear having electrostatic teeth ona circumferential surface thereof, which could be microminiaturized asgears for transmitting power to a micromachine, are provided by makinguse of the film formation techniques and fine processing techniques usedin a semiconductor process; and a method of manufacturing these gears.

DISCLOSURE OF THE INVENTION

The method of manufacturing gears according to the present invention isadapted to separately manufacture upper and lower halves, which are tobe joined to each other at their opposed cross-sectionally circularportions, of a worm the axis of rotation of which is horizontal orinclined with respect to a base plate, including the steps of forming alower half molding flask having the shape of a cross-sectionallysemicircular worm, depositing a metal or other material for forming agear portion and an upper half of the gear in the molding flask, andforming the deposited material to the shape of the upper half of theworm by etching the same material.

Another method of manufacturing gears according to the present inventionis a method of manufacturing a worm the axis of rotation of which isperpendicular to or inclined with respect to a base plate surface,adapted to form one stage or not larger than one stage of a helicalbody, for example, a half thereof at a time, and piling up the helicalstructures. In this method, a circumferential surface portion of thegear can also be formed out of a material different from the materialfor a gear body so that the circumferential portion has a projectiontype shape. After forming a desired helical structure, a groove portionmade of a material different from the material for the gear and baseplate is removed by wet etching to complete the gear. A worm the axis ofrotation of which is inclined with respect to a base plate surface canbe manufactured by inclining the worm body at an arbitrary angle withrespect to a base plate surface while one stage or not larger than onestage, for example, a half of the helical structure is formed at a time.

Still another method of manufacturing gears according to the presentinvention is a method of manufacturing a spur gear the axis of rotationof which is horizontal to or inclined with respect to a base platesurface, by using a manufacturing procedure identical with that used inthe manufacturing of horizontal worm, i.e., by forming a lower half ofthe gear first, and then an upper half thereof.

A further method of manufacturing gears according to the presentinvention is a method of manufacturing a bevel gear the axis of rotationof which is perpendicular to a base plate surface, the bevel gear beingable to be made by one film formation and processing step, a gearhorizontal with respect to a base plate surface or a bevel gear inclinedwith respect the same being made half at a time, i.e., the upper andlower halves of the gear being made separately. A gear having such ashape that does not permit the gear to be formed at even upper and lowerhalves thereof separately is formed by using a method of molding asmaller part of the gear at a time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a columnar worm;

FIG. 2 is a side view of the columnar worm;

FIG. 3 is a plan view for describing the method of manufacturing a worm,the axis of rotation of which is horizontal with respect to a base platesurface, to be used for a micromachine in a first embodiment of thepresent invention;

FIG. 4 is a sectional view for describing the method of manufacturing aworm, the axis of rotation of which is horizontal with respect to a baseplate surface, to be used for a micromachine in the first embodiment ofthe present invention;

FIG. 5 is a sectional view for describing the method of manufacturing aworm, the axis of rotation of which is perpendicular to a base platesurface, to be used for a micromachine in a second embodiment of thepresent invention;

FIG. 6 is a sectional view for describing another method ofmanufacturing a worm, the axis of rotation of which is perpendicular toa base plate surface, to be used for a micromachine in the secondembodiment of the present invention;

FIG. 7 is a plan view for describing the method of manufacturing a spurgear, the axis of rotation of which is horizontal with respect to a baseplate surface, to be used for a micromachine in a third embodiment ofthe present invention;

FIG. 8 is a sectional view for describing the method of manufacturing aspur gear, the axis of rotation of which is horizontal with respect to abase plate surface, to be used for a micromachine in the thirdembodiment of the present invention;

FIG. 9 is a side view for describing a bevel gear, the axis of rotationof which is perpendicular to a base plate surface, to be used for amicromachine in the third embodiment of the present invention;

FIG. 10 is a sectional view for describing the method of manufacturing abevel gear, the axis of rotation of which is perpendicular to a baseplate surface, to be used for a micromachine in a fourth embodiment ofthe present invention;

FIG. 11 is a perspective view for describing a gear, the axis ofrotation of which is inclined with respect to a base plate surface, tobe used for a micromachine in a fifth embodiment of the presentinvention;

FIG. 12 is a sectional view for describing the method of manufacturingthe gear, the axis of rotation of which is inclined with respect to abase plate surface, to be used for a micromachine in the fifthembodiment of the present invention;

FIG. 13 shows the completion of a magnetic gear or an electrostatic gearfor a micromachine in another embodiment of the present invention, andis a plan view showing a worm gear the axis of rotation of which ishorizontal with respect to a base plate surface;

FIG. 14 shows the completion of a magnetic gear or an electrostatic gearfor a micromachine in another embodiment of the present invention, andis a side view of a worm gear the axis of rotation of which ishorizontal with respect to a base plate surface;

FIG. 15 shows the completion of a magnetic gear or an electrostatic gearfor a micromachine in another embodiment of the present invention, andis a side view of a spur gear the axis of rotation of which ishorizontal with respect to a base plate surface;

FIG. 16 shows the completion of a magnetic gear or an electrostatic gearfor a micromachine in another embodiment of the present invention, andis a side view of a bevel gear the axis of which is perpendicular to abase plate surface;

FIG. 17 is a perspective view of a spur gear the axis of rotation ofwhich is perpendicular to a base plate surface; and

FIG. 18 is a perspective view of a combination of a worm and a wormgear.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in detail in accordance withwhat are shown in the attached drawings.

The embodiments of the present invention will be described withreference to the drawings.

A worm using magnetic teeth and electrostatic teeth is gearing formed bycombining a hand drum type worm gear and a spur gear type worm geartogether in addition to a columnar gear, or gearing formed by combininga barrel type worm gear and a dish type worm gear together.

Projection type teeth, magnetic teeth and electrostatic teeth are madeby film formation techniques and fine processing techniques, which areused in a semiconductor process and the like, with a gear body of aworm, worm gear, spur gear, bevel gear, etc. The film formationtechniques include vacuum evaporation, a sputtering method, a platingmethod and the like, while the fine processing techniques includephotolithography, an etching method and the like. Furthermore, thetechniques obtained by suitably combining these techniques can be usedin practice.

(First Embodiment)

A method of manufacturing a worm the axis of rotation of which ishorizontal with respect to a base plate surface will be described. FIG.3 is an explanatory drawing illustrating in plan the procedure formanufacturing such a worm.

This worm is manufactured by carrying out in order a step (FIG. 3(1)) offorming recesses (bearing portions 9 and a region 14 constituting aclearance 4 between a worm gear and sides of a base plate 3) on the baseplate 3, so as to rotate the worm 1, a step (FIG. 3(2)) of forming molds12 used to form a lower half region of the worm 1, a step (FIG. 3(3)) ofdepositing a material 5 for the worm 1 to the height equal to that ofthe lower half region formed in the step of (FIG. 3(2)) plus an upperhalf of the worm 1, and a step (FIG. 3(4)) of forming the upper half ofthe worm 1.

Each of these steps will now be described in detail. FIGS. 4(1) to (13)are sectional views showing the procedures for manufacturing a worm.

Concerning forming the region 14, which constitutes the void 3 betweenthe worm gear and sides of the base plate, in such a manner that thegear can be rotated, a photosensitive agent 20 is applied (FIG. 4(1)) toan upper surface of a base plate 3 first. The photosensitive agent maynot be applied directly to the base plate. Other material may bedeposited on the base plate, and a gear may be formed on this depositedmaterial.

A pattern is drawn (FIG. 4(2)) on the photosensitive agent 20 by usingEB direct exposure, a reflective exposure system or a projectionexposure system and the like. During the drawing of the pattern, anexposure value of the photosensitive agent is controlled by regulatingan electron beam or a light shielding film on a mask, in such a mannerthat the photosensitive agent 20 comes to have a semicircularcross-sectional shape 21 as shown in the drawing. Namely, in the EBdirect exposure, the electron beam is applied to resist by varying thequantity of the electron beam continuously, and the photosensitive agentis developed, the resist being thereby processed so that the resist hasan arbitrary inclined or curved cross-sectional shape. There is also amethod of forming a worm by holding down the quantity of the electronbeam and changing the number of application of the electron beam.

Next, in the reflective exposure system or projection exposure system, aworm of a desired shape is formed by regulating a quantity of reflectedlight on a mask in use by a method of setting the thickness of the lightshielding film, a method of setting the arrangement of fine holes formedin the light shielding film, or a method of a combination of thesemethods, and thereby continuously controlling the exposure value. Thismethod will hereinafter be referred to as an exposure value controlmethod. In addition to this method, directly etching a material with anion beam or a laser beam also enables a worm to be formed.

An etching operation 22 is carried out (FIG. 4(3)) so that the etchingcan be done perpendicularly to a base plate surface with thephotosensitive agent 20, which was formed in the step of FIG. 4(2), usedas a mask, and so that etching rates of the photosensitive agent and amaterial to be etched, i.e. those of a material of the base plate andphotosensitive agent in this embodiment become equal to each other. Thismethod will hereinafter be referred to as a transfer etching method.

A material 13 different from that for the gear is deposited (FIG. 4(4)).

The region of the material 13 deposited in the step of FIG. 4(4) whichis other than a groove-packing region is removed (FIG. 4(5)).

A mold for a lower half of the gear is then formed. First, aphotosensitive agent 20 is applied (FIG. 4(6)) to the base plate so thata thickness of the photosensitive agent becomes equal to a radius of thegear.

A mold 23 for a lower half of the gear is exposed, developed and cured(FIG. 4(7)) by the same exposure control method as was used in the stepof FIG. 4(2).

A mold 24 for a lower half of the gear is transfer formed (FIG. 4(8)) bytransfer etching the material by the same method as was used in the stepof FIG. 4(3).

Next, a gear is formed.

A material 5 for the gear is deposited on the base plate 3 (FIG. 4(9)).The thickness of a film of the material 5 used at this time is set sothat the largest thickness of a gear-forming region be equal to thediameter of the gear.

A photosensitive agent 20 is applied to this material (FIG. 4(10)). Thethickness of the photosensitive agent is regulated so as to become equalto the radius of the gear.

On the photosensitive agent 20 thus applied to the material, an upperhalf 25 of the gear is formed (FIG. 4(11)) by an exposure value controlmethod.

The shape of the upper half 25 of the gear formed at an upper portion bya transfer etching method is transfer formed (FIG. 4(12)) on a groundmaterial by etching.

Finally, the material 13 existing between the base plate 3 and gear 1 isremoved to form a clearance 4, and the gear is thereby renderedrotatable (FIG. 4(13)).

Besides the columnar worm, various types of worms, such as a hand drumtype worm, a barrel type worm and the like can also be formed.

(Second Embodiment)

A method of manufacturing a worm the axis of rotation of which isperpendicular to a base plate surface will be described. FIG. 5 is asectional view showing the procedure for manufacturing this worm.

FIGS. 5(1) to 5(4) shows a step of making a base of helixes.

In order to rotate a gear, a portion 31 corresponding to a clearancebetween a bearing portion 30 and a base plate 3 is formed (FIG. 5(1)).

A material 5 for the gear and a photosensitive agent 20 are deposited(FIG. 5(2)) on the base plate 3 to a thickness equal to the height ofone stage of the base of helixes.

The shape of the photosensitive agent 20 is exposed by the exposurevalue control method to form one helical turn (FIG. 5(3)).

The photosensitive agent 20 is transfer etched to form (FIG. 5(4)) abase 5 ₁ of the gear.

A portion corresponding to a groove 1 a of the gear 1 is then formed.This groove 1 a is formed by depositing a material 13 different from thegear forming material 5 on a front surface of the base plate, and then aresist on this deposited material. The resultant product is exposed,developed and etched by using a regular mask on which a ring typepattern is drawn in a photolithographic step, to form the groove so thatthe material 13 remains therein. After the etching operation finishes,the resist is removed (FIG. 5(5)).

The portions constituting projecting portions of the gear and a centralportion of the gear are then formed. Namely, the material 5 for the gearis deposited, and these portions are made (FIG. 5(6)) by the same methodas is used in the steps of FIGS. 5(2) to (4).

The step of FIG. 5(5) and step of FIG. 5(6) are then carried outrepeatedly until a desired number of teeth 5 ₁, 5 ₂, 5 ₃ . . . , 5 _(n)are formed, to make teeth in a piled manner (FIG. 5 (7)). These piledteeth are formed out of a material 13 different from that 5 of the gear.A material 31 corresponding to an upper clearance portion is thendeposited between upper bearing portions, and bearing portions areformed thereon.

Finally, the material 31 joined to upper and lower portions is removed(FIG. 5(8)). As a result, a structure capable of being rotated as a wormgear is formed. Although a rotary shaft 8 and bearing portions 9 areshown parallel to each other in FIG. 5(8) which shows a completed wormgear, it is possible to form each of these parts so as to have a curvedsurface for the purpose of reducing friction, sharpen one of the parts,and change the shapes of the parts. It is also possible to form ballbearings between the rotary shaft 8 and bearing portions 9 by anexposure value control method and a transfer etching method.

Another method different from the above-mentioned method will bedescribed. FIG. 6 illustrates a method, which is different from theabove method, of making a worm the axis of rotation of which isperpendicular to the base plate surface.

In order to rotate a gear, a bearing portion and a portion 31corresponding to a clearance between a base plate 3 and gear are formed.A tooth portion having a surface inclined in one direction is thenformed (FIG. 6(1)) out of a material 5 for the gear. A groove portion ofthe gear and a half a ring corresponding to a portion of magnetic teethor electrostatic teeth is formed (FIG. 6(2)) out of a material 13different from the material 5 for the gear. In order to form the otherhalf of the ring, a tooth portion having a surface inclined in thedirection opposite to the direction of inclination of the first-formedhalf and a groove portion (magnetic tooth and electrostatic tooth) arethen formed (FIGS. 6(3) and (4)). These steps are then carried outalternately to form a gear having a desired number of teeth.

Besides a columnar worm, various shapes of worms including a hand drumtype worm, a barrel type worm and the like can also be formed.

(Third Embodiment)

A method of manufacturing a spur gear the axis of rotation of which ishorizontal with respect to a base plate surface will be described. Thisembodiment is directed to a spur gear having four projections.

This spur gear is formed by carrying out successively in order to rotatethe gear a step (FIG. 7(1)) of forming a region 14 of a clearanceportion 4 between the base plate and gear and bearing portions 9, a step(FIG. 7(2)) of forming a molding flask 12 for a lower half of the gear,a step (FIG. 7(3)) of depositing a gear-forming material 5, and a step(FIG. 7(4)) of forming an upper half of the gear.

Each of these steps will be described in detail. FIGS. 8(1) to (8) aresectional views showing the procedure for manufacturing a spur gear.

In order that a spur gear can be rotated, a groove 40 is made in a baseplate 3, and filled with a material different from those for the gear 1and base plate 3. A photosensitive agent 20 is applied (FIG. 8(1)) to anupper surface of the base plate thus formed.

The photosensitive agent is exposed by an exposure value control method,and a lower half 42 of the spur gear is formed (FIG. 8(2)).

A molding flask 43 corresponding to a lower half of the gear is formed(FIG. 8(3)) by a transfer etching operation.

A material 5 for the gear is deposited (FIG. 8(4)) to a thickness equalto a diameter of the gear 4.

A photosensitive agent 20 is applied (FIG. 8(5)) to the material 5 to athickness equal to a radius of the gear.

The shape 1A of the upper half of the gear is formed (FIG. 8(6)) by theexposure value control exposure.

A ground material is transfer etched to form (FIG. 8(7)) the gear 1.

The material 41 in the clearance between the base plate 13 and gear 1 isremoved (FIG. 8(8)).

Although a spur gear having four projections is shown in thisembodiment, spur gears having projections the number of which is otherthan four can also be formed.

(Fourth Embodiment)

A method of manufacturing a bevel gear the axis of rotation of which isperpendicular to a base plate surface will be described. FIG. 9 is aside view of the bevel gear.

In order that a gear can be rotated, a groove is formed in a base plate3, and filled (FIG. 10(1)) with a material 31 different from those ofthe gear and base plate.

A material 5 for the gear is deposited on the base plate in which thegroove is formed (FIG. 10(2)).

A photosensitive agent 20 is applied (FIG. 10(2)) to an upper surface ofthe material 5.

The photosensitive agent is exposed by an exposure value control method,to form (FIG. 10(3)) a shape 50 of a bevel gear.

A transfer etching operation is carried out to form (FIG. 10(4)) a bevelgear 51.

The material 31 existing between the base plate and gear is removed, tomake a bevel gear (FIG. 10(5)).

(Fifth Embodiment)

A method of manufacturing a gear the axis of rotation is inclined withrespect to a base plate surface will be described. FIG. 11 is aperspective view showing a contour of a gear 1 the rotary shafts 8 ofwhich are inclined with respect to a base plate surface. This embodimentis applied to a worm, a spur gear and a bevel gear the axes of rotationof which are inclined with respect to base plate surfaces.

A resist 20 is applied to an upper surface of a base plate 3 or amaterial, which is other than the base plate, formed on the base plate(FIG. 12(1)).

The base plate 3 is etched back, and the shape 60 of the resist istransfer etched (FIG. 12(2)) on the base plate (ground material).

A film 61 of a material different from that of the base plate 3 isformed (FIG. 12(3)) on an outer surface of the base plate 3.

A material 5 for the gear is deposited on the base plate 3, and a resist20 is applied (FIG. 12(4)) to an upper surface of the material 5.

The base plate 3 is etched back, and the shape of the resist is transferetched (FIG. 12(5)) on the base plate 3.

The film 61 formed in the step of FIG. 12(3) is etched to remove (FIG.12(6)) the same.

The present invention includes the following modes of embodiment inaddition to the gears in the above embodiments. FIG. 13 to FIG. 16 showcompleted examples of magnetic gears and electrostatic gears. FIG. 13shows a worm the axis of rotation of which is horizontal with respect toa base plate surface, FIG. 14 a worm perpendicular to a base platesurface, FIG. 15 a spur gear horizontal with respect to a base platesurface, and FIG. 16 a bevel gear perpendicular to a base plate surface.Referring to these drawings, magnetic teeth are shown in a black andwhite intermediate color. Either a N-pole or a S-pole is provided. TheN-pole and S-pole can also be arranged adjacently to each other. Theelectrostatic teeth can also be arranged on portions of a black andwhile intermediate color.

It will be added that gears which are other than the above-describedgears, and which have complicated shapes, for example, various types ofgears the axes of rotation of which are inclined with respect to baseplate surfaces, bevel gears the axes of rotation of which are horizontalwith respect to base plate surfaces, and the like can also bemanufactured by using the above-mentioned exposure value control methodand transfer etching method.

Industrial Applicability

As described above, the gear according to the present invention is agear having projection type teeth on a circumferential surface thereof,or a gear having magnetic teeth on a circumferential surface thereof, ora gear having electrostatic teeth on a circumferential surface thereof.The method of manufacturing such gears according to the presentinvention is capable of forming gears, such as a worm gear, a spur gear,a bevel gear and the like, and also other gears having more complicatedshapes, to all of which one of the above-mentioned types of teeth areapplied, by using film formation techniques including vapor deposition,sputtering, plating techniques, CVD, oxidation process and the like, andfine processing techniques including photolithography, etching, FIB andthe like, this method thereby enabling teeth and gear to be formedcollectively in the same process. Especially, subminiature gears in theorder of submicron, micron and millimeter can be manufactured as gearsfor micromachines. The gears according to the present invention can alsobe utilized as fine hole making drills formed by modifying worms.

1. A method of manufacturing a worm gear system, said system including aworm gear having an outer surface, and a base plate having a topsurface, wherein said gear has an axis of rotation that is horizontalwith respect to said top surface of said base plate; said system havinga clearance portion between said gear and said base plate so that saidgear can be rotated, said clearance portion having an outer surfacedefining said top surface of said base plate and an inner surfacedefining said outer surface of said gear; the method comprising thesteps of: providing a first material for forming said base plate;applying a first photosensitive agent onto said base plate uppersurface; applying an exposure value control method (EVCM) to said firstphotosensitive agent for forming a first shape defining said bottomsurface of said clearance portion; transfer etching said first shapeonto said top surface of said base plate, wherein said firstphotosensitive agent is used as a mask; depositing a second material forforming said clearance portion, said second material being differentfrom said base plate, said second material being deposited aftercompleting said transfer etching method; removing excess secondmaterial, wherein said excess includes material that is not required forforming said clearance portion; applying a second photosensitive agentto said base plate upper surface; applying an EVCM to said secondphotosensitive agent for forming a second shape defining said innersurface of said clearance portion; transfer etching said second shapeonto said second material, wherein said second photosensitive agent isused as a mask; depositing a third material for forming said gear ontosaid base plate; applying a third photosensitive agent to an uppersurface of said deposited gear material; applying an EVCM to said thirdphotosensitive agent for forming a third shape defining an upper half ofsaid gear; transfer etching said third shape onto said gear material,wherein said third photosensitive agent is used as a mask; and removingany excess said third material from said clearance portion.
 2. A methodof manufacturing a worm gear system, said system having a worm gear,said gear including a plurality of helical turns, at least a first groveportion, and at least a first projection and a central portion; saidsystem having bottom and top base plates, said bottom base plate havinga top surface and said top base plate having a bottom surface, said gearhaving an axis of rotation that is perpendicular to said top surface ofsaid bottom base plate; said system having bottom and top bearingportions and bottom and top clearance portions between said gear andrespective bottom and top base plates, said bottom and top bearingportions and said bottom and top clearance portions each having a topsurface; the method comprising the step of: providing said bottom baseplate; forming said bottom bearing portion and said bottom clearanceportion on said top surface of said bottom base plate; depositing afirst material for forming said gear onto both of said top surface ofsaid bottom bearing portion and said bottom clearance portion and saidtop surface of said bottom base plate; depositing a first photosensitiveagent onto said first material to a thickness corresponding to a firsthelical turn of said gear; applying an exposure value control method(EVCM) to said first photosensitive agent for forming a first shapedefining said first helical turn; transfer etching said shape of firsthelical turn onto said gear material, wherein said first photosensitiveagent is used as a mask; forming said first groove of said gear by: 1)depositing a second material, different from said first material, ontosaid first material; 2) depositing a second photosensitive agent ontosaid second material; 3) depositing a resist onto said secondphotosensitive agent; 4) using said second photosensitive agent as amask and applying photolithography to draw a ring-type pattern on saidmask for transferring said pattern onto said second material; and 5)removing said resist; forming said first projecting portion and centralportion of said gear by: 1) depositing a third material for forming saidgear onto said grove to a thickness corresponding to that of a secondhelical turn; 2) depositing a third photosensitive agent onto said thirdmaterial, to a thickness corresponding to that of said second helicalturn; 3) applying an exposure value control method (EVCM) to said thirdphotosensitive agent for forming a second shape defining said secondhelical turn; and 4) transfer etching said second shape onto said thirdmaterial; forming a gear laminate of a desired height by successivelyforming grooves, projecting portions and central portions; depositing aforth material onto said gear laminate for forming said upper bearingand clearance portion; providing said top base plate; depositing saidbottom surface of said top base plate onto said top surface of said topbearing and clearance portion; and removing said top and bottomclearance material portions.
 3. A method of manufacturing a spur gearsystem, said system having a spur gear and a base plate, said base platehaving a top surface, said spur gear having an axis of rotation that ishorizontal with respect to said top surface of said base plate; saidsystem having a clearance portion between said gear and said base plateso that said gear can be rotated; said method comprising the steps of:providing said base plate; forming a groove in said base plate; fillingsaid base plate groove with a first material for forming said clearanceportion, wherein said first material is different from said gear andbase plate; applying a first photosensitive agent onto said top surfaceof said base plate and onto said clearance portion; applying an exposurevalue control method (EVCM) to said first photosensitive agent forforming a first shape defining a lower half of said spur gear; transferetching said first shape onto said first material; depositing a secondmaterial defining said gear onto said first material; applying a secondphotosensitive agent onto said second material; applying an EVCM to saidsecond photosensitive agent for forming a second shape defining an upperhalf of said gear; transfer etching said second shape onto said secondmaterial; and removing said clearance portion.
 4. A method ofmanufacturing a bevel gear system, said system having a bevel gear and abase plate, said base plate having a top surface, said bevel gear havingan axis of rotation that is perpendicular to said top surface of saidbase plate; said method comprising the steps of: providing said baseplate; forming a groove in said base plate; depositing a first materialfor forming a clearance portion onto said groove, said first materialbeing different from said gear and said base plate; depositing a secondmaterial for different from said gear onto said base plate upper surfaceand onto said first material; depositing a photosensitive agent ontosaid second material; applying an exposure value control method (EVCM)to said photosensitive agent for forming a first shape defining saidbevel gear; transfer etching said first shape onto said gear material;and removing any excess said second material from said clearanceportion.